JP2020036393A - Required charging time estimation method, required charging time estimation device and electric vehicle - Google Patents

Abstract

To provide a charging time estimation method and a charging time estimation device capable of accurately estimating a required charging time, and provide an electric vehicle comprising a function for estimating an accurate charging time.SOLUTION: A vehicle controller 4 commands a charging current value to a battery charger 7, such that a battery 61 is charged by a multistage constant current charging system. The vehicle controller 4 estimates a required time for charging the battery 61 (104). The vehicle controller 4 executes: a total capacity acquisition step (105) of acquiring total capacity of the battery 61; a current value acquisition step (107) of acquiring a charging current value in each of constant current charging steps; an achievable charging rate acquisition step (108) of acquiring an achievable charging rate that can be achieved in each of the constant current charging steps; and a step (109) of estimating a required time until completing the charging of the battery 61 on the basis of the total capacity of the battery 61, the charging current value in each of the constant current charging steps and the achievable charging rate in each of the constant current charging steps.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method and an apparatus for estimating a time required for charging a secondary battery. Further, the present invention relates to an electric vehicle provided with a required charging time estimation device.

  The electric vehicle includes an electric motor as a drive source for running the vehicle, and a battery that supplies power to the electric motor. The battery is a rechargeable secondary battery, and a lithium ion battery is a typical example. Generally, a CC-CV method is applied to charging of a lithium ion battery. In the CC-CV method, constant current charging (CC charging) with a constant current value is performed in a state where the battery voltage is low. When the battery voltage rises to a predetermined voltage by the constant current charging, the battery voltage is switched to a constant voltage charging (CV charging) with a constant voltage value, and the battery is charged to a full charge by the constant voltage charging.

Patent Literature 1 discloses that the required charging time required to complete charging is displayed to improve usability. Furthermore, Patent Literature 1 points out that the estimation accuracy of the required charging time is reduced due to fluctuations in charging current and voltage due to the internal resistance of the secondary battery and a reduction in the maximum battery capacity due to battery deterioration. . To solve this problem, the invention of Patent Document 1, the coefficient G _I divided by the charging current value actually supplied ideal value of the charging current in the constant current charging (base current) to secondary battery, A coefficient _GCAPA obtained by dividing the current value of the maximum battery capacity of the secondary battery by its initial value is obtained. The constant current charging time T _CC is obtained by multiplying these coefficients G _I and G _CAPA by the basic estimated value of the constant current charging time. The coefficient _{G I,} the constant voltage charging time _{T CV} is obtained by multiplying the _{G CAPA} to basic estimated value of the constant voltage charging time. Then, by adding these, the required charging time T _CHG = T _CC + TC _CV is obtained.

Japanese Patent No. 5742998

  During the constant voltage charging period, the charging current changes every moment, so it is not easy to accurately estimate the constant voltage charging time. In Patent Literature 1, the basic estimated value of the constant voltage charging time is calculated by a conventionally known method using the battery temperature information and the remaining battery capacity information. However, since the charging current value fluctuates especially due to a change in the internal resistance value, a method for calculating a charging current value that changes every moment during constant-voltage charging with high accuracy has not been established. Therefore, in the method of Patent Document 1, the accuracy of estimating the constant voltage charging time is not high, and the accuracy of estimating the required charging time is not always sufficient. Therefore, accurate information cannot be provided to the user. .

  Thus, one embodiment of the present invention provides a charging time estimation method and a charging time estimation device that enable accurate estimation of the required charging time. Further, one embodiment of the present invention provides an electric vehicle having a function of estimating an accurate charging time.

  One embodiment of the present invention provides a method for estimating a required time for charging a secondary battery by a multi-stage constant current charging method in which a plurality of constant current charging steps having different charging current values are sequentially performed. This method comprises: a total capacity obtaining step of obtaining the total capacity of the secondary battery; a current value obtaining step of obtaining a charging current value in each constant current charging step; and a reachable charge reachable by each constant current charging step. Attainable charging rate obtaining step of obtaining a rate, the secondary capacity based on the total capacity of the secondary battery, the charging current value at each of the constant current charging steps, and the attainable charging rate of each of the constant current charging steps. Estimating the time required to complete charging of the battery.

According to this method, since the charging of the secondary battery is performed by the multi-stage constant current charging method, the respective charging current values in the plurality of constant current charging steps are constant values. Therefore, the time required for each constant current charging step can be accurately estimated based on the total capacity of the secondary battery, the charging current value, and the attainable charging rate.
In the constant voltage charging method, since the charging current value changes every moment, it is difficult to improve the accuracy of estimating the required charging time. On the other hand, in the multi-stage constant current charging method, the constant current charging is performed stepwise, so that the stepwise fluctuation of the charging current value is controlled, and the charging current value in each stage is constant. Can be increased in estimation accuracy.

In one embodiment of the present invention, the attainable charging rate obtaining step includes a step of searching a map defining characteristics of the attainable charging rate with respect to the charging current value. According to this method, the attainable charging rate can be obtained by a map search, and therefore, by preparing a map representing the characteristics of the secondary battery, it is possible to estimate the required charging time with high accuracy.
In one embodiment of the present invention, the attainable charge rate obtaining step obtains the attainable charge rate according to the temperature of the secondary battery. In this method, since the temperature characteristics of the secondary battery are taken into account, it is possible to estimate the required charging time with higher accuracy.

In one embodiment of the present invention, the attainable charging rate obtaining step includes a step of searching a map defining characteristics of the attainable charging rate with respect to the charging current value and the temperature of the secondary battery. In this method, by preparing a map reflecting the temperature characteristics of the secondary battery, the required charging time can be obtained with high accuracy.
In one embodiment of the present invention, the attainable charge rate obtaining step includes a step of correcting the attainable charge rate according to the deterioration of the secondary battery. According to this method, the deterioration of the secondary battery is taken into account, so that the accuracy of estimating the required charging time can be further improved.

  In one embodiment of the present invention, the method comprises the steps of: obtaining an actual attained charging rate actually reached by a certain constant current charging step; and performing the constant current charging step before the completion of the constant current charging step. And comparing the reachable charge rate acquired in the reachable charge rate acquisition step with the actual reached charge rate. Then, the step of correcting the reachable charging rate corrects the reachable charging rate in each constant current charging step based on the comparison result.

According to this method, the attainable charging rate is corrected according to the actually reached charging rate (actual attained charging rate), so that it is possible to more accurately estimate the required charging time.
One embodiment of the present invention provides a required charging time estimating apparatus including a controller programmed to execute the above-described required charging time estimating method. With this configuration, it is possible to provide a device that can accurately estimate the required charging time.

One embodiment of the present invention provides an electric vehicle including a secondary battery, an electric motor for driving the vehicle with electric power generated by the secondary battery, and the charging time estimation device. With this configuration, it is possible to provide an electric vehicle having a function of estimating the required charging time with high accuracy.
In one embodiment of the present invention, the electric vehicle further includes a charger for charging the secondary battery by a multi-stage constant current charging method. Then, the controller is programmed to control the charger to execute the plurality of constant current charging steps. With this configuration, it is possible to provide an electric vehicle having a function of charging the secondary battery and a function of estimating the required charging time with high accuracy.

  In one embodiment of the present invention, the electric vehicle further includes a display device that displays the estimated required charging time. With this configuration, it is possible to realize an electric vehicle having a function of displaying the charging time estimated with high accuracy and providing the charging time to the user.

  According to the present invention, the required charging time of the secondary battery can be accurately estimated.

FIG. 1 is a block diagram showing an electrical configuration of a main part of an electric vehicle including a required charging time estimating apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram for explaining a functional configuration of a vehicle controller provided in the electric vehicle. FIG. 3 is a conceptual diagram for explaining the multi-stage constant current charging method. FIG. 4 is a diagram illustrating an example of a map of a reachable charging rate stored in a memory of the vehicle controller. FIG. 5 is a flowchart for explaining a processing example of the vehicle controller regarding charging of the battery by the multi-stage constant current charging method. FIG. 6 is a flowchart for describing a processing example of the vehicle controller regarding the estimation and display of the required charging time. FIG. 7 is a block diagram for describing an electrical configuration of an electric vehicle according to another embodiment of the present invention. FIG. 8 is a flowchart for explaining a processing example of the vehicle controller regarding charging of two batteries by the multi-stage constant current charging method. FIG. 9 is a flowchart for explaining a processing example of the vehicle controller regarding the estimation and display of the required charging time. FIG. 10 is a flowchart illustrating a specific example of step S55 in FIG. FIG. 11 is a flowchart illustrating a specific example of step S56 in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a block diagram showing an electrical configuration of a main part of an electric vehicle 1 including a required charging time estimating apparatus according to an embodiment of the present invention. The electric vehicle 1 can take various vehicle forms such as an electric motorcycle, an electric four-wheeled vehicle, and an electric snowmobile. An electric vehicle is a vehicle that includes an electric motor as a drive source for running the vehicle. A so-called hybrid vehicle that includes an internal combustion engine as a drive source in addition to the electric motor may also be one form of the electric vehicle.

  The electric vehicle 1 of this embodiment includes an electric motor 2 that generates a driving force for running the vehicle, a motor controller 3 that controls driving of the electric motor 2, and a vehicle controller 4 that controls each part of the vehicle. And a display device 5 for displaying various information to be provided to the driver. Electric vehicle 1 further includes a battery 61 for storing electric power to be supplied to electric motor 2, and a charger 7 for charging battery 61. The motor controller 3, the vehicle controller 4, the display device 5, the battery 61, and the charger 7 are connected to an in-vehicle LAN 8, which is a local area network built in the vehicle.

  The battery 61 is a rechargeable battery, that is, a secondary battery. The motor controller 3 executes motor drive control for supplying electric power generated by the battery 61 to the electric motor 2 and regenerative control for charging the battery 61 with electric power generated by the electric motor 2 when the vehicle decelerates. The charger 7 is a device for charging the battery 61 with electric power supplied from an AC power supply provided in a home or a charging station. The charger 7 is connected so that current can be supplied to the battery 61. More specifically, charging line 9 from which charger 7 outputs a direct current is connected to power supply line 10 from battery 61 to motor controller 3.

  The electric motor 2 may be a three-phase AC brushless motor. The rotation information of the electric motor 2 is detected by a rotation sensor 11 such as a resolver and is input to the motor controller 3. The motor controller 3 includes a microcomputer 31 and a drive circuit 32. The drive circuit 32 specifically includes an inverter circuit. The microcomputer 31 controls the drive circuit 32 according to the rotation information detected by the rotation sensor 11, thereby generating a motor drive control for supplying electric power from the battery 61 to the electric motor 2 and generating the electric motor 2. The regenerative control for supplying electric power to the battery 61 is executed. The motor controller 3 controls the drive circuit 32 according to a drive current value (regenerative current value) provided from the vehicle controller 4 via the in-vehicle LAN 8.

  Vehicle controller 4 includes microcomputer 40. The microcomputer 40 includes a processor 41 and a memory 42. The memory 42 stores a program P executed by the processor 41. When the processor 41 executes the program P, the microcomputer 40 realizes a plurality of functions. One example of the function is a function as a required charging time estimating device for estimating the required charging time of the battery 61. In addition, the microcomputer 40 sends a drive current value (regenerative current value) to the motor controller 3 via the in-vehicle LAN 8 in response to a drive output command (specifically, an acceleration command and a deceleration command) which is an operation input of the driver. Execute the function to command. Further, the microcomputer 40 instructs the charging current value to the charger 7 via the in-vehicle LAN 8, thereby executing a function as a charging controller for charging the battery 61 by the multi-stage constant current charging method. The memory 42 stores an SOC map M that defines a reachable SOC (State of Charge: charging rate) according to the charging current value. The microcomputer 40 commands the charging current value to the charger 7 with reference to the SOC map M, and estimates the required charging time. Further, the microcomputer 40 executes a function of instructing the display device 5 to display contents via the in-vehicle LAN 8. One example of the display content is the charging time.

  The display device 5 includes a microcomputer 51 and a display panel 52 such as a liquid crystal display device. The microcomputer 51 has a function as a display controller that controls display on the display panel 52. The microcomputer 51 receives a display content command from the vehicle controller 4 via the in-vehicle LAN 8, and controls the display panel 52 according to the display content. Thereby, various information is displayed on the display panel 52. The displayed information includes, for example, vehicle speed, traveling distance, remaining capacity of battery 61, required charging time, and the like.

  Charger 7 includes a microcomputer 71, an AC / DC converter 72, and a charging circuit 73. The AC / DC converter 72 converts an alternating current (AC) into a direct current (DC). The charging circuit 73 includes a charging switch 74 controlled by the microcomputer 71, and outputs a DC current generated by the AC / DC converter 72 to the charging line 9 as a charging current having a controlled constant current value. The charging switch 74 is typically a switching element configured by a semiconductor element. The microcomputer 71 controls the charging switch 74 so that a charging current of a charging current value instructed from the vehicle controller 4 via the in-vehicle LAN 8 is output.

  The battery 61 includes a plurality of battery cells 63, a battery managing unit (Battery Managing Unit) 64, a current breaker 67, a current sensor 68, and a temperature sensor 69. The battery cell 63 is a unit for storing electric power, and is composed of, for example, a secondary battery cell such as a lithium ion battery. The temperature sensor 69 measures the temperature of the battery cell 63 and inputs the measurement result to the battery managing unit 64. The current breaker 67 is interposed between the power supply line 10 and the battery cell 63, and opens and closes a circuit. The current breaker 67 includes, for example, a switching element (semiconductor element) whose opening and closing are controlled by the battery managing unit 64. The current sensor 68 detects a current flowing into and out of the battery cell 63 via the power supply line 10, and inputs a detection result to the battery managing unit 64.

The battery managing unit 64 is constituted by a microcomputer, and includes a processor 65 and a memory 66. When the processor 65 executes a program stored in the memory 66, the battery managing unit 64 realizes a plurality of functions.
One example of the function of the battery managing unit 64 is a calculation of a state of charge (SOC) based on an output signal of the current sensor 68. That is, the battery managing unit 64 integrates the values of the current flowing into and out of the battery cell 63 based on the output signal of the current sensor 68, thereby obtaining the SOC of the battery 61. The obtained SOC is stored in the memory 66 as the current SOC. The memory 66 also stores information on the overall capacity of the battery 61. The battery managing unit 64 also has a function of monitoring the output voltage of the battery 61.

  Another example of the function of the battery managing unit 64 is communication with the vehicle controller 4 via the in-vehicle LAN 8. Through this communication, information such as the temperature information of the battery cell 63, the current SOC, the current battery voltage, and the like are passed to the vehicle controller 4. Further, the battery managing unit 64 can receive a command from the vehicle controller 4 and open and close the current breaker 67, for example. Further, the battery managing unit 64 may have a function of detecting an abnormality such as an abnormality in the temperature of the battery cell and shutting off the current breaker 67 to protect the battery 61 by itself.

  FIG. 2 is a block diagram for explaining a functional configuration of the vehicle controller 4. As described above, when the processor 41 executes the program P, the vehicle controller 4 substantially functions as a plurality of function processing units. The plurality of function processing units include a charging control unit 101, a display control unit 102, a motor output control unit 103, and a required charging time estimation unit 104.

  When charging the battery 61, the charging control unit 101 sequentially instructs the charger 7 to perform a plurality of stages of charging current values (constant current values) for sequentially executing a plurality of constant current charging steps. Execute control. When charging the battery 61, the charging control unit 101 gives an opening / closing command for opening / closing the current breaker 67 of the battery 61 to the battery managing unit 64 as necessary.

The display control unit 102 instructs the display device 5 to display contents. The display contents include vehicle speed, remaining battery capacity, required charging time, and the like.
The motor output control unit 103 instructs the motor controller 3 on a drive current value (regeneration current value) of the electric motor 2.
The required charging time estimating unit 104 estimates the required time until the end of charging when charging the battery 61. The time required for full charge may be estimated, or the time required for a predetermined charge state, for example, a charge rate set by the user may be estimated. The required charging time estimating unit 104 includes a total capacity obtaining unit 105, a current remaining capacity obtaining unit 106, a charging current value obtaining unit 107, a reachable SOC obtaining unit 108, and a required time calculating unit 109.

  The total capacity acquisition unit 105 acquires the total capacity of the battery 61. The information on the total capacity of the battery 61 may be stored in the memory 42 in advance, or may be obtained by communication with the battery managing unit 64. The current remaining capacity acquisition unit 106 acquires information on the current remaining capacity of the battery 61, specifically, the current SOC, by communicating with the battery managing unit 64. The charging current value acquiring unit 107 acquires a charging current value applied in a plurality of constant current charging steps of the multi-stage constant current charging. This charge current value may be stored in the memory 42 in advance, or a charge current value that is actually applied may be acquired from the charge control unit 101.

  Reachable SOC acquisition section 108 acquires information on the reachable SOC based on the charging current value applied in each constant current charging step. In this embodiment, the reachable SOC is obtained by searching the SOC map M stored in the memory 42. The SOC that can be reached by a constant charging current value depends on the temperature of the battery cell 63. Thus, the memory 42 stores an SOC map M that defines reachable SOCs corresponding to a plurality of battery cell temperatures. Reachable SOC acquiring section 108 communicates with battery managing unit 64 to acquire current temperature information of battery cell 63, and, based on the current temperature, reaches reachable SOC corresponding to charging current value to SOC map M. Search from.

The required time calculation unit 109 calculates the required time until the completion of charging based on the total capacity of the battery 61, the charging current value in each constant current charging step, and the attainable SOC.
As described above, the vehicle controller 4 includes: a total capacity obtaining step (105) for obtaining the total capacity of the battery 61; a current value obtaining step (107) for obtaining a charging current value in each constant current charging step; Reachable charging rate obtaining step (108) for obtaining the reachable charging rate that can be reached by the charging step, the total capacity of the battery 61, the charging current value in each constant current charging step, and the reachable charging in each constant current charging step. A step (109) of estimating a required time until the charging of the battery 61 is completed based on the rate.

  FIG. 3 is a conceptual diagram for explaining the multi-stage constant current charging method. The multi-stage constant current charging method includes a plurality of constant current charging steps. The example of FIG. 3 includes first, second, third and fourth constant current charging steps. In the first to fourth constant current charging steps, constant current charging is performed using the first charging current value I1, the second charging current value I2, the third charging current value I3, and the fourth charging current value I4, respectively. However, I1> I2> I3> I4> 0. The fourth charging current value I4 in the final constant current charging step is set to a value that allows the battery 61 to be fully charged. Each constant current charging step ends when the battery voltage reaches a predetermined upper limit voltage value. Therefore, the reachable SOC in each constant current charging step is the SOC when the battery voltage reaches the upper limit voltage value.

  FIG. 4 is a diagram for explaining an example of the SOC map M stored in the memory 42 of the vehicle controller 4. The SOC map M defines the SOC characteristics that can be reached with respect to the charging current value. The charging current value and the SOC that can be reached by the charging current value have a substantially linear correlation, and the smaller the charging current value, the larger the reachable SOC. On the other hand, there is also a correspondence between the battery cell temperature and the attainable SOC, and even at the same charging current value, the attainable SOC decreases as the battery cell temperature T decreases. The SOC map M defines the relationship of the reachable SOC to the charging current value for a plurality of different battery cell temperatures T.

  FIG. 4 shows map data in the case where the battery cell temperature T is 0 ° C., 25 ° C., and 40 ° C., but maps for more battery cell temperatures may be prepared. More specifically, the plurality of maps are set at appropriate temperature intervals (for example, at 5 ° C. intervals) so as to correspond to an appropriate range according to the operation guarantee temperature of electric powered vehicle 1, for example, a temperature range of −10 ° C. to 60 ° C. It is preferable to prepare the data.

When there is no map data corresponding to the actual battery cell temperature, a reachable SOC corresponding to the battery cell temperature can be obtained by an interpolation operation using two map data close to the actual battery cell temperature.
Next, the principle of estimating the required charging time will be described.
The reachable SOC is obtained by searching the SOC map M based on the charging current value and the battery cell temperature in a certain constant current charging step, and performing an interpolation operation as necessary. Based on the reachable SOC (%), the current SOC (%), and the total capacity (Ah) of the battery 61, the charging capacity (step charging) to be charged in the constant current charging step is given by the following equation (1). Capacity (Ah)).

Total capacity x (reachable SOC-current SOC) = step charge capacity ... (1)
Then, the required time of the constant current charging step (step required time (h)) is obtained by dividing the step charging capacity by the charging current value (A) of the constant current charging step as shown in the following equation (2). Is found.
Step charging capacity / charging current value = Step required time ... (2)
In order to determine the step required time of another constant current charging step executed after the constant current charging step, the following equation (3) may be used instead of equation (1) when calculating the step charging capacity. Equation (3) is obtained by replacing “current SOC” in equation (1) with a achievable SOC in the immediately preceding constant current charging step (the SOC reached in the previous step). By substituting the obtained step charging capacity into equation (2), the required step time is obtained.

Total capacity x (reachable SOC-previous step reached SOC) = step charge capacity ... (3)
In this way, the required steps in the currently executed constant current charging step and the constant current charging step to be executed in the future are obtained, and by calculating the sum of them, the required charging time can be estimated.
FIG. 5 is a flowchart for explaining a processing example of the vehicle controller 4 regarding charging of the battery 61 by the multi-stage constant current charging method. The vehicle controller 4 acquires the current SOC of the battery 61 and the current battery cell temperature by communicating with the battery managing unit 64 (steps S1 and S2). Based on these, the vehicle controller 4 determines a constant current charging step in the multi-stage constant current charging method (step S3). More specifically, the SOC that can be reached by the respective charging current values of the plurality of constant current charging steps is obtained by searching the SOC map M, and the most achievable charging current value among the charging current values with the attainable SOC greater than the current SOC is obtained. A constant current charging step corresponding to a large charging current value is selected. The vehicle controller 4 commands the charging current value of the selected constant current charging step to the charger 7 (step S4). Thereby, charger 7 supplies the current of the commanded charging current value to charging line 9. Thus, the constant current charging at the charging current value is performed.

  While the constant current charging is being performed, the vehicle controller 4 acquires the battery voltage from the battery managing unit 64 (Step S5), and compares the acquired battery voltage with the upper limit voltage value (Step S6). When the battery voltage reaches the upper limit voltage value, charging with the charging current value in the constant current charging step can no longer be performed. Then, when the battery voltage reaches the upper limit voltage value (step S6: YES), the vehicle controller 4 switches to the next constant current charging step, that is, the constant current charging step with a smaller charging current value (step S10). If the current constant-current charging step is the final constant-current charging step, that is, the constant-current charging step with the smallest charging current value (step S9: YES), the switching is not performed and the charging ends.

  When the battery voltage reaches the upper limit voltage value (Step S6: YES), the vehicle controller 4 acquires the current SOC from the battery managing unit 64 (Step S7). The SOC at this time is the SOC (actually reached SOC) actually reached by the charging current value in the constant current charging step. Therefore, the vehicle controller 4 calculates a correction coefficient for correcting the reachable SOC (a value obtained by a map search) using the actual arrival SOC (step S8), and stores it in the memory 42. A specific example of the correction coefficient is represented by the following equation (4).

Correction coefficient = Actual SOC / Achievable SOC (4)
The difference between the actual SOC and the reachable SOC obtained by the map search is mainly due to a decrease in the total capacity (chargeable capacity) due to the deterioration of the battery 61. Therefore, the ratio between the actual attainable SOC and the attainable SOC becomes substantially equal at an arbitrary charging current value. Therefore, the correction coefficient of Expression (4) can be used for correcting the attainable SOC at an arbitrary charging current value.

Step S8 of obtaining the correction coefficient corresponds to a step of comparing the reachable SOC obtained by the map search with the actually reached SOC, and the correction coefficient of Expression (4) corresponds to the comparison result.
FIG. 6 is a flowchart for explaining a processing example of the vehicle controller 4 regarding estimation and display of the required charging time. The vehicle controller 4 repeats this process at a predetermined cycle. The vehicle controller 4 communicates with the battery managing unit 64 to acquire information on the overall capacity of the battery 61, the current SOC, and the battery cell temperature (steps S11, S12, S13). In addition, a charging current value in the currently executed constant current charging step is obtained (step S14). Further, the vehicle controller 4 searches the SOC map M based on the current charging current value and the battery cell temperature (step S15), performs an interpolation operation as necessary, and performs the interpolation operation according to the currently executed constant current charging step. A reachable SOC is obtained (step S16). Further, the vehicle controller 4 corrects the reachable SOC by multiplying the obtained reachable SOC by the above-described correction coefficient (step S17). The vehicle controller 4 uses the corrected reachable SOC to determine the required time of the constant current charging step according to the equations (1) and (2) (step S18).

  Further, if the constant current charging step for which the step required time is obtained is not the final constant current charging step (step S19: NO), the vehicle controller 4 proceeds to step S14 for the next constant current charging step (step S20). Repeat the process. That is, the charging current value of the next constant current charging step to be executed is obtained (step S14), and the SOC map M is searched based on the charging current value and the current battery cell temperature (step S15). A possible SOC is determined (step S16). Further, the attainable SOC is corrected by a correction coefficient (step S17), and the required time of the constant current charging step is obtained from the corrected attainable SOC according to the equations (3) and (2) (step S17). S18). The same processing is sequentially repeated until the final constant current charging step at which the attainable SOC before correction obtained by the map search becomes 100% (steps S19 and S20), whereby the step required time of all the constant current charging steps to be executed ( Step S18) is obtained.

The vehicle controller 4 obtains the required charging time until full charging by adding the required step times thus obtained (step S21). The vehicle controller 4 instructs the display device 5 to display the calculated required charging time (step S22). Thereby, the estimated value of the required charging time is displayed on the display device 5.
As the vehicle controller 4 repeats the process, the estimated value of the required charging time changes in accordance with the progress of charging. Therefore, not only at the start of charging but also during charging, the time required for charging until the charging is completed can be displayed on the display device 5.

  There may be a case where it is desired to display the required charging time up to the designated SOC of less than 100% instead of the required charging time until the full charge. In this case, for the constant current charging step of the reachable SOC equal to or less than the designated SOC, the step required time is calculated in the same manner as described above, and for the constant current charging step of the reachable SOC exceeding the designated SOC, In the equations (1) and (3), the “reachable SOC” may be replaced with the designated SOC to determine the step required time.

  Instead of specifying the SOC, a value of the traveling distance required by the user may be specified. For example, the vehicle controller 4 may calculate a required capacity required for traveling the traveling distance designated by the user, obtain an SOC corresponding to the required capacity, and set the SOC as the designated SOC. Further, the user specifies a point on the map, obtains the amount of power required for traveling from the current position to the specified point as a required capacity, calculates an SOC corresponding to the required capacity, and sets the SOC as the specified SOC. It may be. More specifically, the travel distance from the current location to the designated point may be determined by the vehicle controller 4 or another processing device, and the required capacity required for traveling the travel distance may be calculated. Then, a designated SOC corresponding to the required capacity may be set.

  As described above, in this embodiment, the charging of the battery 61 is performed by the multi-stage constant current charging method, and the charging current values in the plurality of constant current charging steps are constant values. Therefore, the step required time of each constant current charging step can be accurately estimated based on the overall capacity of the battery 61, the charging current value, and the attainable SOC. Accordingly, the accuracy of estimating the required charging time can be improved, so that the user of the electric vehicle 1 can be provided with an accurate remaining time until the completion of charging.

  In this embodiment, an SOC map M representing the characteristics of the battery 61 is used. The SOC map M defines the characteristics of the attainable SOC with respect to the charging current value. Since the reachable SOC at each constant current charging step can be obtained by searching the SOC map M, the required time for the step can be accurately estimated, and the accuracy of estimating the required time until the completion of charging can be improved accordingly.

Moreover, since the SOC map M defines the characteristics of the reachable SOC according to the temperature of the battery 61, the step required time can be estimated in consideration of the temperature characteristics of the battery 61. As a result, the required time can be estimated with higher accuracy.
Further, in this embodiment, the actual attained SOC at each constant current charging step is obtained, and the correction coefficient is obtained by the above equation (4) based on the actual attained SOC. The reachable SOC obtained by the map search is corrected using the correction coefficient. This makes it possible to accurately estimate the required step time even when the total chargeable capacity decreases due to aging of the battery 61. Therefore, since the deterioration of the battery 61 is taken into account, it is possible to more accurately estimate the required charging time.

FIG. 7 is a block diagram for describing an electrical configuration of an electric vehicle 1 according to another embodiment of the present invention. 7, the same reference numerals are given to the corresponding parts of the respective parts shown in FIG.
In this embodiment, two batteries 61 and 62 are provided, and these are connected to the power supply line 10 in parallel. The two batteries 61 and 62 are equivalent products in this embodiment, and the same reference numerals are assigned to the corresponding parts of the internal components of the batteries 61 and 62 in order to avoid redundant description. .

The motor controller 3 supplies the electric power generated by the two batteries 61 and 62 to the electric motor 2. When the electric motor 2 is performing a regenerative operation, the two batteries 61 and 62 are charged by the electric power generated by the electric motor 2.
The charging line 9 connected to the charger 7 is connected to the two batteries 61 and 62 in parallel. Therefore, the two batteries 61 and 62 can be charged by the charger 7. The vehicle controller 4 controls the operation of the charger 7 to charge the two batteries 61 and 62 by a multi-stage constant current charging method. Further, the vehicle controller 4 estimates the time required for the charging, and causes the display device 5 to display the estimated time.

  When there is a relatively large difference between the SOCs of the two batteries 61 and 62, the vehicle controller 4 preferentially charges the battery with a low SOC, and leads to a state where the SOCs of the two batteries 61 and 62 are close to each other. That is, the vehicle controller 4 controls only the battery having a low SOC to the charger 7 by controlling the current breakers 67 of the batteries 61 and 62 via the battery managing unit 64. Thereafter, when the SOCs of the two batteries 61 and 62 reach a state of approximation, the vehicle controller 4 controls the current breaker 67 via the battery managing unit 64 to charge the two batteries 61 and 62 with the charger. 7 and charge them simultaneously.

  FIG. 8 is a flowchart for explaining a processing example of the vehicle controller 4 regarding charging of the two batteries 61 and 62 by the multi-stage constant current charging method. The vehicle controller 4 acquires the current SOC and the current battery cell temperature of the two batteries 61 and 62 by communicating with the battery managing units 64 of the two batteries 61 and 62 (steps S31 and S32). Hereinafter, the current SOC of the battery 61 is referred to as “current SOC1”, and the current SOC of the battery 62 is referred to as “current SOC2”. The current battery cell temperature of the battery 61 is referred to as “battery cell temperature 1”, and the current battery cell temperature of the battery 62 is referred to as “battery cell temperature 2”.

  Vehicle controller 4 sets the charging mode to one of charging mode 1, charging mode 2 and charging mode 3 based on current SOC1 and current SOC2. The charging mode 1 is a mode in which only the battery 61 is charged. The charging mode 2 is a mode in which only the battery 62 is charged. The charging mode 3 is a mode for charging both of the batteries 61 and 62 in parallel.

  Specifically, the vehicle controller 4 compares the current SOC1 and the current SOC2, and checks whether or not the difference between them is equal to or greater than a predetermined threshold value Δ (> 0). When the difference between the SOCs is equal to or larger than the threshold value Δ, the charging mode is set so as to preferentially charge a battery having a small SOC. That is, if the current SOC2−current SOC1 ≧ Δ (step S33: YES), the charging mode 1 is set to charge the battery 61 preferentially (step S34). If current SOC1−current SOC2 ≧ Δ (step S37: YES), charge mode 2 is set to charge battery 62 preferentially (step S38). If −Δ <current SOC1−current SOC2 <Δ (step S37: NO), the charging mode 3 is set to simultaneously charge the two batteries 61 and 62 in parallel (step S41).

  In the charging mode 1 (step S34), the vehicle controller 4 gives a command to the battery managing unit 64 of the battery 61 to turn on the current breaker 67. Further, the vehicle controller 4 gives an instruction to the battery managing unit 64 of the battery 62 to shut off the current breaker 67. Thereby, the battery 61 is connected to the charging line 9, and the battery 62 is disconnected from the charging line 9. In this state, the vehicle controller 4 determines a constant current charging step for charging the battery 61 by the multi-stage constant current charging method (step S35). More specifically, the SOC that can be reached by each of the charging current values in the plurality of constant current charging steps is obtained by searching the SOC map M, and the largest SOC among the charging current values that are larger than the current SOC1 is reachable. A constant current charging step corresponding to the charging current value is selected. The vehicle controller 4 instructs the charger 7 of a charging current value of the selected constant current charging step (hereinafter, referred to as “charging current value 1”) (step S36). Thereby, charger 7 supplies the current having the commanded charging current value 1 to charging line 9. Thus, the constant current charging of the charging current value 1 is executed. Thereafter, by repeating the operation from step S31, the current SOC1 approaches the current SOC2 while an appropriate constant current charging step is selected (that is, the charging current value 1 is appropriately changed). If the determination in step S33 is negative, the process proceeds to step S37 and shifts to the charging mode 3 (step S41).

  Similarly, in the charging mode 2 (step S38), the vehicle controller 4 gives a command to the battery managing unit 64 of the battery 61 to shut off the current breaker 67. Further, the vehicle controller 4 gives a command to the battery managing unit 64 of the battery 62 to turn on the current breaker 67. Thereby, the battery 61 is disconnected from the charging line 9, while the battery 62 is connected to the charging line 9. In this state, the vehicle controller 4 determines a constant current charging step for charging the battery 62 by the multi-stage constant current charging method (step S39). More specifically, the SOC that can be reached by each of the charging current values in the plurality of constant current charging steps is obtained by searching the SOC map M, and the largest SOC among the charging current values that are larger than the current SOC2 is reachable. A constant current charging step corresponding to the charging current value is selected. Vehicle controller 4 instructs charger 7 of a charging current value (hereinafter, referred to as “charging current 2”) in the selected constant current charging step (step S40). Thereby, charger 7 supplies the current having the commanded charging current value 2 to charging line 9. Thus, the constant current charging of the charging current value 2 is performed. Thereafter, by repeating the operation from step S31, the current SOC2 approaches the current SOC1 while an appropriate constant current charging step is selected (that is, the charging current value 2 is appropriately changed). If the determination in step S37 is negative, the process shifts to charging mode 3 (step S41).

  In this embodiment, since the batteries 61 and 62 are equivalent, a common SOC map M can be used for the batteries 61 and 62. Of course, individual SOC maps may be used for the batteries 61 and 62. In the charging modes 1 and 2, the SOC maps M corresponding to or common to the batteries 61 and 62 are searched. Also in the charging mode 3, the same SOC map M, that is, the SOC map M corresponding to or common to the batteries 61 and 62 can be used.

  In the charging mode 3 (step S41), the vehicle controller 4 gives an instruction to the battery managing units 64 of the batteries 61 and 62 that all the current breakers 67 should be made conductive. Thereby, both the batteries 61 and 62 are connected to the charging line 9. In this state, the vehicle controller 4 determines a constant current charging step for charging the batteries 61 and 62 in parallel by the multi-stage constant current charging method (step S42).

  In the constant current charging step of the charging mode 3, the charging current value is preferably set to be larger than the corresponding constant current charging step of the charging mode 1 and the charging mode 2, for example, about twice as large. This is because, in the charging mode 3, the current supplied by the charger 7 is divided into the batteries 61 and 62. Therefore, the vehicle controller 4 obtains an SOC that can be reached by a half of the charging current value of each of the plurality of constant current charging steps by searching the SOC map M. Then, a constant current charging step corresponding to the largest charging current value among the charging current values at which the attainable SOC is larger than the current SOC (current SOC1 or current SOC2) is selected.

The vehicle controller 4 instructs the charger 7 of a charging current value (hereinafter, referred to as “charging current value 3”) of the selected constant current charging step (step S43). Thereby, charger 7 supplies the current having the commanded charging current value 3 to charging line 9. In this way, the batteries 61 and 62 are each charged at a constant current with a current approximately half of the charging current value 3.
While the constant current charging is being performed, the vehicle controller 4 acquires the battery voltage from the battery managing unit 64 of the batteries 61 and 62 (step S44), and either one of the two acquired battery voltages (for example, low). Is compared with the upper limit voltage value (step S45). When the battery voltage to be compared reaches the upper limit voltage value, charging with the charging current value in the constant current charging step can no longer be performed. Then, when the battery voltage to be compared reaches the upper limit voltage value (step S45: YES), the vehicle controller 4 switches to the next constant current charging step, that is, the constant current charging step with a smaller charging current value (step S49). ). If the current constant-current charging step is the final constant-current charging step, that is, the constant-current charging step with the smallest charging current value (step S48: YES), the charging is completed without switching the constant-current charging step.

  When the battery voltage to be compared reaches the upper limit voltage value (step S45: YES), the vehicle controller 4 acquires the current SOC1 and the current SOC2 from the battery managing units 64 of the batteries 61 and 62 (step S46). At this time, the current SOC1 and the current SOC2 are the SOCs (actually reached SOCs) actually reached in the batteries 61 and 62 based on the charging current value in the constant current charging step. Therefore, the vehicle controller 4 calculates a correction coefficient for correcting the attainable SOC (the value obtained by the map search) using the actual arrival SOC (step S47), and stores the correction coefficient in the memory 42. A specific example of the correction coefficient is as in the above equation (4). This correction coefficient can be used for correcting the attainable SOC at an arbitrary charging current value, as in the first embodiment.

  FIGS. 9, 10 and 11 are flowcharts for explaining a processing example of the vehicle controller 4 regarding estimation and display of the required charging time. The vehicle controller 4 repeats this process at a predetermined cycle. The vehicle controller 4 communicates with the battery managing unit 64 of the two batteries 61 and 62 to communicate the total capacity of the battery 61 (hereinafter referred to as “total capacity 1”) and the total capacity of the battery 62 (hereinafter “total capacity 2”). Is acquired (step S50). Further, the vehicle controller 4 communicates with the battery managing unit 64 of the two batteries 61 and 62 to acquire the current SOC1, the current SOC2, the battery cell temperature 1 and the battery cell temperature 2 (steps S51 and S52). Further, the vehicle controller 4 acquires the currently executing charging mode (step S53). The vehicle controller 4 estimates each required time of the constant current charging step of the charging mode 1 if the charging mode 1 is being executed (step S55), and if the charging mode 2 is being executed, the constant current charging of the charging mode 2 The time required for each step is estimated (step S56). When neither of the charging modes 1 and 2 is being executed, that is, if the charging mode 3 is being executed, the vehicle controller 4 estimates each required time of the constant current charging step of the charging mode 3 (steps S57 to S57). S63).

  FIG. 10 shows an example of estimating the time required for each constant current charging step in the charging mode 1. The vehicle controller 4 acquires the charging current value 1 in the constant current charging step in the charging mode 1 (Step S71). The vehicle controller 4 first searches the SOC map M based on the charging current value 1 and the battery cell temperature 1 in the currently executed constant current charging step (step S72), and performs an interpolation operation as necessary, The SOC that can be reached by the currently executed constant current charging step (hereinafter referred to as “reachable SOC1”) is obtained (step S73). Further, the vehicle controller 4 corrects the reachable SOC1 by multiplying the obtained reachable SOC1 by the above-described correction coefficient (step S74). Using the corrected reachable SOC1, the vehicle controller 4 obtains the step required time of the constant current charging step according to the equations (1) and (2) (step S77). However, the total capacity, the reachable SOC, the current SOC, and the charging current value in Expressions (1) and (2) are replaced with the total capacity 1, the reachable SOC1, the current SOC1, and the charging current value 1, respectively. When the corrected reachable SOC1 is equal to or higher than the current SOC of the other battery 62 that is not in a charged state, that is, the current SOC2 (step S75: YES), the corrected reachable SOC1 is replaced with the current SOC2 (step S75). S76).

  By repeating the same calculation processing sequentially until the corrected reachable SOC1 becomes equal to or higher than the current SOC2 until the constant current charging step (steps S78 and S79), the required time of each constant current charging step in the charging mode 1 is obtained. However, when calculating the step required time of the constant current charging step that is not currently being executed (step S77), equation (3) is applied instead of equation (1).

  The same applies to the estimation of the time required for each constant current charging step in the charging mode 2, an example of which is shown in FIG. The vehicle controller 4 acquires the charging current value 2 in the constant current charging step in the charging mode 2 (Step S81). The vehicle controller 4 first searches the SOC map M based on the charging current value 2 and the battery cell temperature 2 in the currently executed constant current charging step (step S82), and performs an interpolation calculation as necessary. The SOC that can be reached by the currently executed constant current charging step (hereinafter, referred to as “reachable SOC2”) is obtained (step S83). Further, the vehicle controller 4 corrects the reachable SOC2 by multiplying the obtained reachable SOC2 by the above-described correction coefficient (step S84). Using the corrected reachable SOC2, the vehicle controller 4 obtains the step required time of the constant current charging step according to the equations (1) and (2) (step S87). However, the total capacity, the reachable SOC, the current SOC, and the charging current value in Expressions (1) and (2) are replaced with the total capacity 2, the reachable SOC2, the current SOC2, and the charging current value 2, respectively. When the corrected reachable SOC2 is equal to or higher than the current SOC of the other battery 61 that is not in a charged state, that is, the current SOC1 (step S85: YES), the corrected reachable SOC2 is replaced with the current SOC1 (step S85). S86).

  The same processing is sequentially repeated until the corrected reachable SOC2 becomes equal to or greater than the current SOC1 (steps S88 and S89), whereby the required time of each constant current charging step in the charging mode 2 is obtained. However, when calculating the step required time of the constant current charging step that is not currently being executed (step S87), equation (3) is applied instead of equation (1).

In this way, when the required time of each constant current charging step of the charging mode 1 or the charging mode 2 is determined, the vehicle controller 4 determines the required time of each step of the charging mode 3 (steps S57 to S63).
That is, the vehicle controller 4 acquires the charging current value 3 in the constant current charging step in the charging mode 3 (Step S57). First, the vehicle controller 4 searches the SOC map M based on the half of the charging current value 3 in the current constant current charging step and the battery cell temperature 1 or the battery cell temperature 2 (step S58). ), An interpolation operation is performed as needed to obtain an SOC that can be reached by the currently executed constant current charging step (hereinafter, referred to as “reachable SOC3”) (step S59). Further, the vehicle controller 4 corrects the reachable SOC3 by multiplying the obtained reachable SOC3 by the above-described correction coefficient (step S60). Using the corrected reachable SOC3, the step required time of the constant current charging step is obtained from the above equations (1) and (2) (step S61). Here, the total capacity, the reachable SOC, the current SOC and the charging current value of the equations (1) and (2) are the sum of the total capacity 1 and the total capacity 2, the reachable SOC3, the average value of the current SOC1 and the current SOC2, respectively. As well as the charging current value 3. When calculating the step required time of the constant current charging step that is not currently being executed, equation (3) is applied instead of equation (1).

By repeating the same process sequentially until the final constant current charging step at which the reachable SOC3 before correction obtained by the map search becomes 100% (steps S62 and S63), the required time of each constant current charging step in the charging mode 3 is reduced. I get it.
The vehicle controller 4 obtains the required charging time until full charging by adding the required step times thus obtained (step S64). Specifically, when the charging mode 1 is being executed, the step required time of each constant current charging step in the charging mode 1 and the step required time of each constant current charging step after the shift to the charging mode 3 are determined. Are calculated, and they are added together to determine the time required for charging until full charge. If the charging mode 2 is being executed, the step required time of each constant current charging step of the charging mode 2 and the step required time of each constant current charging step after the transition to the charging mode 3 are obtained. These are added together to determine the time required for charging until full charge. If the charging mode 3 is being executed, the calculation of the step required time in the charging modes 1 and 2 is omitted, and the step required time of each constant current charging step being executed and not being executed in the charging mode 3 is obtained. The time required for charging until the battery is fully charged is calculated by adding the total.

The vehicle controller 4 instructs the display device 5 to display the required charging time thus obtained (step S65). Thereby, the estimated value of the required charging time is displayed on the display device 5.
As the vehicle controller 4 repeats the process, the required charging time changes according to the progress of charging. Therefore, the time required until the charging is completed can be displayed on the display device 5 not only at the start of charging but also during the charging.

  As described in the first embodiment, there may be a case where it is desired to display the required charging time up to the designated SOC of less than 100% instead of the required charging time until the full charge. In this case, for the constant current charging step of the reachable SOC equal to or less than the designated SOC, the step required time is calculated in the same manner as described above, and for the constant current charging step of the reachable SOC exceeding the designated SOC, In step (1), the “reachable SOC” may be replaced with the specified SOC to determine the required step time.

  As described above, in this embodiment, the charging by the multi-stage constant current charging method is applied to the two batteries 61 and 62, the step required times of the respective constant current charging steps are obtained, and these are summed to obtain the required charging time. Desired. Thereby, similarly to the case of the first embodiment, it is possible to accurately estimate the time required to complete charging. That is, the effects described in the first embodiment can be similarly obtained.

  In addition, in this embodiment, when there is a significant difference between the current SOCs of the two batteries 61 and 62, one battery with a lower current SOC is charged preferentially. Thus, when the current SOCs of the two batteries 61 and 62 become similar, the two batteries 61 and 62 are connected in parallel to the charger 7 and are charged simultaneously. The priority charging step of one battery and the simultaneous charging step of the two batteries 61 and 62 are both performed by a multi-stage constant current charging method. Therefore, at any stage, the time required for the constant current charging step can be accurately estimated. Therefore, even when there is a difference between the current SOCs of the two batteries 61 and 62 at the start of charging, it is possible to estimate the required charging time with high accuracy.

  The same applies to the case where three or more batteries are provided in the electric vehicle 1, and the required charging time can be estimated with high accuracy. In general, when there are a plurality of batteries to be charged and there is a significant difference between the current SOCs, one or more batteries having the lowest current SOC may be preferentially charged. When the SOC of the battery to be charged preferentially reaches or almost reaches the current SOC of another battery, the other battery may be added to the charging target.

The two embodiments of the present invention have been described above, but the present invention can be embodied in other forms.
For example, in the above-described embodiment, the vehicle controller 4 has a function as a charging time estimating device. However, another processing device provided in the electric vehicle 1 may have a function as a charging time estimating device. Good.

  Further, in the above-described embodiment, the electric vehicle 1 is provided with the charger 7, but the electric vehicle 1 does not have to include the charger 7. For example, the charger 7 may be provided at a charging station. The vehicle controller 4 is communicably connected to such a charger 7 so that the vehicle controller 4 can instruct a charging current value to the charger 7 to perform multi-stage constant current charging.

Further, the display device 5 of the electric vehicle 1 does not need to have a function of displaying the required charging time. For example, the charging station or the charger may be provided with a display device for displaying the required charging time.
Further, the function of estimating the required charging time need not be provided in electric powered vehicle 1. For example, a charging time estimating device that estimates the required charging time by performing the same arithmetic processing as the vehicle controller 4 in the above-described embodiment may be provided in the charging station or the charger. More specifically, a charger provided in the charging station may have a function as a required charging time estimation device.

Further, in the above-described embodiment, the correction coefficient is obtained by Expression (4) based on the attainable SOC and the actual attained SOC. However, instead of obtaining such a correction coefficient, the arrival of the corresponding charging current value is not determined. The possible SOC may be replaced by the actual SOC.
In addition, various design changes can be made within the scope of the matters described in the claims.

  Reference Signs List 1 electric vehicle, 2 electric motor, 3 motor controller, 31 microcomputer, 32 drive circuit, 4 vehicle controller, 40 microcomputer, 41 processor, 42 memory, P program, MSOC map, 5 display device, 51 microcomputer, 52 Display panel, 61, 62 battery, 63 battery cell, 64 battery managing unit, 65 processor, 66 memory, 67 current breaker, 68 current sensor, 69 temperature sensor, 7 charger, 71 microcomputer, 72 AC / DC converter , 73 charging circuit, 74 charging switch, 8 in-vehicle LAN, 9 charging line, 10 power supply line, 11 rotation sensor, 101 charging control unit, 102 display control unit, 103 motor output control unit, 104 charging Required time estimating section, 105 overall capacity acquisition unit, 106 current remaining capacity acquisition unit, 107 charge current value acquisition unit, 108 reachable SOC acquisition unit, 109 required time calculation unit, I1 to I4 charging current value, T cell temperature

Claims (10)

A method for estimating a required time for charging a secondary battery by a multi-stage constant current charging method in which a plurality of constant current charging steps having different charging current values are sequentially performed,
An overall capacity obtaining step of obtaining an overall capacity of the secondary battery,
A current value obtaining step of obtaining a charging current value in each constant current charging step,
Reachable charging rate obtaining step of obtaining a reachable charging rate that can be reached by each constant current charging step,
Estimating a time required to complete charging of the secondary battery based on a total capacity of the secondary battery, a charging current value in each of the constant current charging steps, and a reachable charging rate of each of the constant current charging steps. And a method for estimating the required charging time.   The charging required time estimating method according to claim 1, wherein the attainable charging rate obtaining step includes a step of searching a map defining characteristics of the attainable charging rate with respect to a charging current value.   The charging time estimating method according to claim 1, wherein the attainable charging rate obtaining step obtains the attainable charging rate according to a temperature of the secondary battery.   The charging time estimating method according to claim 3, wherein the attainable charging rate obtaining step includes a step of searching a map that defines characteristics of the attaining charging rate with respect to the charging current value and the temperature of the secondary battery.   The charging time estimation method according to any one of claims 1 to 4, wherein the reachable charging rate obtaining step includes a step of correcting the reachable charging rate in accordance with deterioration of the secondary battery. A step of acquiring an actual reaching charging rate actually reached by a certain constant current charging step;
Comparing the achievable charging rate obtained in the achievable charging rate obtaining step with respect to the constant current charging step before the completion of the constant current charging step and the actual reaching charging rate. ,
The charging required time estimating method according to claim 5, wherein the step of correcting the reachable charging rate corrects the reachable charging rate in each constant current charging step based on the comparison result.   An apparatus for estimating a required charging time, comprising a controller programmed to execute the method for estimating a required charging time according to any one of claims 1 to 6. Secondary batteries,
An electric motor for driving a vehicle with electric power generated by the secondary battery,
An electric vehicle comprising: the charging time estimation device according to claim 7. The battery further includes a charger for charging the secondary battery by a multi-stage constant current charging method,
9. The electric vehicle according to claim 8, wherein the controller is programmed to control the charger to execute the plurality of constant current charging steps.   The electric vehicle according to claim 8, further comprising a display device that displays the estimated required charging time.

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